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<base href="https://bugs.llvm.org/">
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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - Optimizer fails to unroll the Coroutine-Loop."
href="https://bugs.llvm.org/show_bug.cgi?id=34293">34293</a>
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<th>Summary</th>
<td>Optimizer fails to unroll the Coroutine-Loop.
</td>
</tr>
<tr>
<th>Product</th>
<td>libraries
</td>
</tr>
<tr>
<th>Version</th>
<td>trunk
</td>
</tr>
<tr>
<th>Hardware</th>
<td>PC
</td>
</tr>
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<th>OS</th>
<td>Linux
</td>
</tr>
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<th>Status</th>
<td>NEW
</td>
</tr>
<tr>
<th>Severity</th>
<td>enhancement
</td>
</tr>
<tr>
<th>Priority</th>
<td>P
</td>
</tr>
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<th>Component</th>
<td>Loop Optimizer
</td>
</tr>
<tr>
<th>Assignee</th>
<td>unassignedbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>peetlugen19@yandex.com
</td>
</tr>
<tr>
<th>CC</th>
<td>llvm-bugs@lists.llvm.org
</td>
</tr></table>
<p>
<div>
<pre>Created <span class=""><a href="attachment.cgi?id=19033" name="attach_19033" title="testcase">attachment 19033</a> <a href="attachment.cgi?id=19033&action=edit" title="testcase">[details]</a></span>
testcase
Test case: <a href="https://godbolt.org/g/esjnb2">https://godbolt.org/g/esjnb2</a>
I've also attached the test-case as an attachment.
LLVM-IR:
define void @printEquivalent()() local_unnamed_addr #0 !dbg !684 {
%1 = tail call i32 (i8*, ...) @printf(i8* getelementptr inbounds ([3 x i8],
[3 x i8]* @.str, i64 0, i64 0), i32 1), !dbg !685
%2 = tail call i32 (i8*, ...) @printf(i8* getelementptr inbounds ([3 x i8],
[3 x i8]* @.str, i64 0, i64 0), i32 3), !dbg !686
ret void, !dbg !687
}
declare i32 @printf(i8* nocapture readonly, ...) local_unnamed_addr #1
define i32 @main() local_unnamed_addr #2 personality i8* bitcast (i32 (...)*
@__gxx_personality_v0 to i8*) !dbg !688 {
br label %1, !dbg !693
; <label>:1: ; preds = %0, %5
%2 = phi i2 [ 0, %0 ], [ %7, %5 ]
switch i2 %2, label %4 [
i2 0, label %5
i2 1, label %3
i2 -2, label %9
]
; <label>:3: ; preds = %1
br label %5, !dbg !826
; <label>:4: ; preds = %1
unreachable, !dbg !824
; <label>:5: ; preds = %1, %3
%6 = phi i32 [ 3, %3 ], [ 1, %1 ]
%7 = phi i2 [ -2, %3 ], [ 1, %1 ]
%8 = tail call i32 (i8*, ...) @printf(i8* getelementptr inbounds ([3 x i8],
[3 x i8]* @.str, i64 0, i64 0), i32 %6), !dbg !828
br label %1, !dbg !693, !llvm.loop !830
; <label>:9: ; preds = %1
ret i32 0, !dbg !832
}
Issue:
The optimizer could have optimized the couroutine into something more like the
two sequential calls to printf. Instead, it isn't able to unroll the
"couroutine-loop".</pre>
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